1. Field of the Invention
The present invention relates to a printing apparatus that performs printing by using a processing liquid which coagulates or insolubilizes a coloring material in ink or ink and to a printing method.
2. Description of the Related Art
In general inkjet printing apparatus, if an image is formed on a print medium called so-called plain paper, water resistance of the image may be insufficient, and solution to that is required. In the meantime, in the case of printing using a relatively large amount of ink to be applied to the print medium such as formation of a color image, feathering or bleeding between colors can easily occur, and formation of a clear image with high density and suppressing these phenomena is also in demand. However, it is difficult to satisfy both the above requirements, and a color image provided with sufficient image fastness and image quality has not been realized yet.
As a method for improving water resistance of an image, ink with a coloring material contained therein having water resistance has been put into practice recently. However, the current ink with improved water resistance is ink that is hardly dissolved in water after being dried in principle, the ink can easily clog a nozzle of a print head, and its water resistance is not necessarily sufficient.
Thus, the improvement of an apparatus by providing a new mechanism improving water resistance and preventing nozzle clogging has been proposed. However, in this case, there is a problem in that the device is complicated and the apparatus cost is drastically increased.
On the other hand, Japanese Patent Laid-Open No. H08-007223 (1996) discloses a technique that improves fastness of an image printed by ink by providing a processing liquid such as a print property improving liquid which causes chemical reaction with printing ink at the same position as a position to provide the ink onto the print medium.
However, in the inkjet printing apparatus, when the ink and the processing liquid is ejected from a print head, micro mist-state droplets other than main droplets landing on the print medium are generated. If these micro ink droplets and processing liquid droplets adhere to an operation portion inside the printing apparatus or a surface in which a ejection port of the print head is formed (hereinafter referred to as a ejection port surface), they react with each other and are firmly fixed at an adhesion portion and deteriorate reliability and life of the apparatus, which is a problem. Therefore, it is necessary to suppress reaction and fixation between the ink and the processing liquid other than on the print medium, and for that purpose, it is necessary to drastically reduce the generation of the micro droplets of the processing liquid (processing-liquid mist). Also, the lower the ink ejection speed is, the smaller the amount of the processing-liquid mist is, and the smaller the ejection amount is, the smaller the mist amount is. Therefore, the reduction of the processing-liquid mist by suppressing the ink ejection speed or the ejection amount is also discussed.
However, there arise a new problem that if the ejection speeds and the ejection amounts of the ink and the processing liquid are reduced in order to reduce the processing-liquid mist, the landing accuracy of the ink is lowered and image quality is deteriorated.